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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 970 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 9.3
  2. 2.√50 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 6.9
  3. 3.√78 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.7 (d) 8.9
  4. 4.√46 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 6.8
  5. 5.√59 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.9
  6. 6.Best estimate of 3823 ÷ 46? (a) 760 (b) 7600 (c) 76
  7. 7.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.6 (d) 8.5
  8. 8.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 4.8 (d) 5.0
  9. 9.Best estimate of 3049 ÷ 41? (a) 760 (b) 76 (c) 7600
  10. 10.Best estimate of 899 ÷ 66? (a) 13 (b) 130 (c) 1300
  11. 11.√75 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  12. 12.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 5.9 (d) 6.0
  13. 13.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  14. 14.Best estimate of 1515 ÷ 28? (a) 5100 (b) 51 (c) 510
  15. 15.√47 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 6.9
  16. 16.√43 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  17. 17.Best estimate of 4887 ÷ 54? (a) 98 (b) 9800 (c) 980
  18. 18.Best estimate of 4638 ÷ 49? (a) 93 (b) 9300 (c) 930
  19. 19.√70 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  20. 20.Best estimate of 4923 ÷ 66? (a) 7000 (b) 700 (c) 70
  21. 21.Best estimate of 1565 ÷ 47? (a) 3100 (b) 31 (c) 310
  22. 22.√35 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.7 (d) 5.9
  23. 23.Best estimate of 681 ÷ 47? (a) 140 (b) 1400 (c) 14
  24. 24.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.2
  25. 25.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.7
  26. 26.Best estimate of 1286 ÷ 76? (a) 1600 (b) 16 (c) 160
  27. 27.Best estimate of 1125 ÷ 26? (a) 380 (b) 3800 (c) 38
  28. 28.Best estimate of 1436 ÷ 56? (a) 240 (b) 24 (c) 2400
  29. 29.Best estimate of 4684 ÷ 62? (a) 78 (b) 7800 (c) 780
  30. 30.Best estimate of 3549 ÷ 76? (a) 4400 (b) 440 (c) 44
  31. 31.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  32. 32.Best estimate of 5296 ÷ 78? (a) 66 (b) 660 (c) 6600
  33. 33.Best estimate of 5868 ÷ 62? (a) 98 (b) 980 (c) 9800
  34. 34.Best estimate of 3641 ÷ 69? (a) 520 (b) 52 (c) 5200
  35. 35.Best estimate of 1613 ÷ 37? (a) 400 (b) 40 (c) 4000
  36. 36.√51 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 7.1 (d) 6.9
  37. 37.Best estimate of 1968 ÷ 61? (a) 330 (b) 3300 (c) 33
  38. 38.√88 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.5 (d) 9.4
  39. 39.Best estimate of 3530 ÷ 37? (a) 88 (b) 8800 (c) 880
  40. 40.Best estimate of 2941 ÷ 32? (a) 9800 (b) 980 (c) 98

Answer key

  1. 9.1
  2. 7.1
  3. 8.8
  4. 6.8
  5. 7.7
  6. 76
  7. 8.3
  8. 5.1
  9. 76
  10. 13
  11. 8.7
  12. 6.1
  13. 8.1
  14. 51
  15. 6.9
  16. 6.6
  17. 98
  18. 93
  19. 8.4
  20. 70
  21. 31
  22. 5.9
  23. 14
  24. 5.4
  25. 5.5
  26. 16
  27. 38
  28. 24
  29. 78
  30. 44
  31. 7.6
  32. 66
  33. 98
  34. 52
  35. 40
  36. 7.1
  37. 33
  38. 9.4
  39. 88
  40. 98

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